for IRS, if you had all your taxes paid in by 4/15 (based on the IRS records) their won't be a penalty.
if you owe but have a reasonable cause or if this is your first time filing late, I would not pay any penalties when filing but let the iRS bill you. once you get the bill you can request abatement based on reasonable cause or citing this is your first time filing late and have taken steps to prevent recurrence in future. Look on line for examples. if you pay and then try requesting abatement the IRS may ignore the request. currently your late filing penalty is 10% of the balance paid after 4/15 + interest. what you risk by not paying now is only the interest portion unless the IRS doesn't respond by 6/16 when the penalty will be 15%